/Engine/Source/Runtime/Engine/Public/AnimationRuntime.h
Combine CurveKeys (that reference morph targets by name) and ActiveAnims (that reference morphs by reference) into the ActiveMorphTargets array.
static void AppendActiveMorphTargets ( const [USkeletalMesh](API\Runtime\Engine\Engine\USkeletalMesh) * InSkeletalMesh, const [TMap](API\Runtime\Core\Containers\TMap)< [FName](API\Runtime\Core\UObject\FName), float > & InMorphCurveAnims, FMorphTargetWeightMap & InOutActiveMorphTargets, [TArray](API\Runtime\Core\Containers\TArray)< float > & InOutMorphTargetWeights )